The present invention generally relates to printing fabric substrates, and more particularly to a printing system that uses a removable backing to support a fabric in a typical digital printing process.
In the fabric printing industry, fabrics are typically colored with coloring agents, such as dyes or pigments, using screen printing technology. Most screen printing technologies employ rotary screen printers that use patterns incorporated into fine metal screens that are shaped into cylindrical forms. The coloring agents, in a print paste form, are pumped through tubing into the cylindrical-shaped screens and subsequently transferred to the fabric through the patterned screens by a squeegee that presses the paste through the screens and onto the fabric. After a print run, the rotary screen printer must be shut down to clean the various colors of print paste from the tubing and screens. The cleanup process is time intensive and environmentally unfriendly because a large amount of effluent is required to clean the print paste from the rotary screen printer. In addition to cleaning the rotary screen printer, a cylindrical screen with a different pattern must be inserted into the rotary screen printer to print a different pattern.
To ensure that the pattern printed on the fabric is not distorted, industrial fabric printing machines stretch and glue the fabric to a moving belt that is run through the printing machine. The moving belt is indexed through the printing machine and the various screen stages. Attaching the fabric to the belt prohibits the fabric from moving with respect to the belt and ensures fabric motion control, as well as adequate registration of the fabric such that the fabric moves in a path corresponding to a movement path of the belt. However, gluing the fabric to the belt is an extremely dirty process and creates a large environmentally unfriendly waste stream from the gluing process and the subsequent washing and stripping processes. These inherent problems make industrial fabric printing processes prohibitive to smaller scale users for use in short run fabric printing, such as an office or a store.
To remedy the need for printing processes available on a smaller than industrial scale, ink-jet printing processes for fabrics have been developed. As known to those of ordinary skill in the art, digital printers utilize minute droplets of ink that are injected from nozzles in the ink-jet printer onto a target surface, such as the fabric. In order to produce an image or pattern with a desired sharpness on the fabric, special fabrics, pre-printing processing steps and post-printing processing steps are used to condition and/or chemically or otherwise fix the colorants to the fibers on the fabric. The pre-printing conditioning steps are used to initially condition the humidity and temperature of the fabric to provide an optional ink reception state for the fabric and the post-conditioning steps are used to xe2x80x9cfixxe2x80x9d the coloring agent to the fabric after the ink has been received by the fabric. The fabric to which the pattern is printed may be backed with a paper layer to reinforce and stabilize the fabric, as well as to produce a barrier to ink blow through. The fabric may also be pre-treated with organic materials in order to increase ink receptivity and reduce the amount of ink spread, which arises from bleeding of the printed ink through fibers in the fabric. As known to those of ordinary skill in the art, the problem of printing on unbacked fabrics using an ink-jet printer is not trivial. The fundamental nature of woven fabrics makes feeding the fabric and printing a pattern on the fabric more complex than ink-jet printing on paper. For instance, fabrics have an almost infinite variation in fabric characteristics due to various factors including, but not limited to, the type of fiber used in the fabric, the fiber weight, the fabric weight, the different blends of materials used in the fiber, the weave pattern used to create the fabric, the environmental conditions existing at the time of printing, the pre-treatments used on the fabric, the surface finish of the fabric, the varying moisture contents of the fiber in the fabric, the non-linear behavior of woven materials, and the difference in fabric behavior between wet and dry fabrics. These factors prohibit the fabrics from moving accurately and uniformly through the printing processes using standard media-moving machines used in ink-jet printers.
In order to stabilize the fabric for passage through an ink-jet printer, the fabric may be laminated to a paper substrate off-line to form a backed fabric. The backed fabric may then be passed through a slightly modified ink-jet printer for the formation of a pattern on the backed fabric. However, the use of off-line paper backings may be costly, time consuming, and may limit the range of fabrics that may be fed through the ink-jet printer. Furthermore, the fabric may be damaged when the fabric is removed from the paper backing. Therefore, a fabric backing system that allows the fabric to pass through an ink-jet printer and produces a printed pattern with a low level of distortion, yet has a low level of damage to the fabric when the fabric is removed from the backing, would be an improvement in the art.
In accordance with the invention, a method for printing a pattern on a layer of fabric removably adhered to a backing substrate is disclosed. The backing substrate comprising a carrier, an adhesive, and a release liner is provided. The release liner is removed from the backing substrate and the layer of fabric is adhered to the adhesive on the backing substrate to form a backed fabric. A pattern is printed on the backed fabric, the fabric is removed from the adhesive on the backing substrate, and the release liner is re-adhered to the adhesive layer of the backing substrate so that the backing substrate can be reused.
A backing substrate for use in a fabric printing process is also disclosed. The backing substrate comprises a carrier, an adhesive, and a release liner. The carrier and the release liner are substantially the same length.
A system for printing a pattern on a backed fabric is also disclosed. The system includes at least one roll of a reusable backing substrate, where the backing substrate is used to support a fabric through a print zone in the printing system. The system also includes at least one roll of fabric. A first roller included in the system is configured to adhere the fabric to the backing substrate to form a backed fabric. The backed fabric is then received by the print zone where a pattern is printed on the backed fabric. The system also comprises at least one device configured to remove the printed fabric from the backing substrate.